BREW-duplicity-CVE-2019-14853 — ecdsa Denial of Service vulnerability in signature verification and signature malleability

Affected: Homebrew: duplicity

## possible DoS in signature verification and signature malleability

### Impact Code using `VerifyingKey.verify()` and `VerifyingKey.verify_digest()` may receive exceptions other than the documented `BadSignatureError` when signatures are malformed. If those other exceptions are not caught, they may lead to program termination and thus Denial of Service

Code using `VerifyingKey.verify()` and `VerifyingKey.verify_digest()` with `sigdecode` option using `ecdsa.util.sigdecode_der` will accept signatures even if they are not properly formatted DER. This makes the signatures malleable. It impacts only applications that later sign the signatures or verify signatures of signatures, e.g. Bitcoin.

All versions between 0.5 and 0.13.2 (inclusive) are thought to be vulnerable. Code before 0.5 may be vulnerable but didn't receive extended analysis to rule this issue out.

### Patches The patches have been merged to `master` branch in https://github.com/warner/python-ecdsa/pull/115. The backported patches for a release in the 0.13 branch are in https://github.com/warner/python-ecdsa/pull/124

They are part of the 0.13.3 release.

There are no plans to backport them to earlier releases.

### Workarounds It may be possible to prevent the Denial of Service by catching also `UnexpectedDER`, `IndexError` and `AssertionError` exceptions. That list hasn't been verified to be complete though. If those exceptions are raised, the signature verification process should consider the signature to b…

CVE-2019-14853

Affected: [UNKNOWN] python-ecdsa

An error-handling flaw was found in python-ecdsa before version 0.13.3. During signature decoding, malformed DER signatures could raise unexpected exceptions (or no exceptions at all), which could lead to a denial of service.

Withdrawn: GHSA-2mrj-435v-c2cr — Duplicate Advisory: possible DoS caused by malformed signature decoding in Pure-Python ECDSA

Withdrawn by the publisher.

Affected: PyPI: ecdsa

## Duplicate Advisory This advisory has been withdrawn because it is a duplicate of GHSA-pwfw-mgfj-7g3g. This link is maintained to preserve external references.

Most recent entries from all

BREW-duplicity-CVE-2019-14853 — ecdsa Denial of Service vulnerability in signature verification and signature malleability

CVE-2019-14853

Withdrawn: GHSA-2mrj-435v-c2cr — Duplicate Advisory: possible DoS caused by malformed signature decoding in Pure-Python ECDSA